Embossed cigarette wrapper with improved holding force

ABSTRACT

A cigarette has a shredded tobacco filler and a paper for wrapping the filler. Many frusto-pyramidal portions biting into the filler are formed so as to be distributed on an inner surface of the paper except on both of the side edge portions of the inner surface. The inner surface, so formed, provides a high coefficient of friction with respect to the shredded tobacco filler. This cigarette contributes to preventing the dropping of shredded tobacco from the cut end of the cigarette.

This application is the national phase under 35 U.S.C. §371 of prior PCTInternational Application No. PCT/JP97/03383 which has an Internationalfiling date of Sep. 24, 1997 which designated the United States ofAmerica, the entire contents of which are hereby incorporated byreference.

TECHNICAL FIELD

The present invention relates to a cigarette whose quality can beimproved and maintained at the time of manufacture and in the subsequentdistribution process.

BACKGROUND ART

One of the most important factors in improving the quality of cigaretteis to prevent shredded tobacco from dropping from the cut end ofcigarette. Therefore, the filling density at the cut end portion ofcigarette is increased as compared with that at other portions, wherebythe shredded tobacco is prevented from dropping from the cut end. Morespecifically, although a cigarette is produced by cutting a tobacco rodas publicly known, the tobacco rod has, at fixed intervals, high-densityportions in which the filling density of shredded tobacco is increased.The tobacco rod is cut at the high-density portions to obtain cigarettesor double cigarettes. The double cigarette having a length twice as longas that of cigarette which has a high-density portion remained at thecenter thereof.

However, even if the tobacco rod is cut at the high-density portions,shredded tobacco sometimes drops from the cut end of cigarette or doublecigarette. Also, when the double cigarette is cut into two cigarettes toproduce a filter cigarette from the double cigarette, shredded tobaccosometimes drops from the cut end of cigarette in the subsequenttransportation process thereof.

Further, not only at the time of manufacture of cigarettes or filtercigarettes as described above, but also in the subsequent distributionprocess, shredded tobacco sometimes drops from the cut end of cigaretteor filter cigarette.

Nowadays, a cigarette manufacturing machine for manufacturing a tobaccorod has a tendency toward higher speed, so that a slip between the paperand the stream of shredded tobacco increases. Such an increase in slipcauses variations in formation and pitch of high-density portions intobacco rod, and also causes the shredded tobacco to be broken. As aresult, the filling density and holding force of shredded tobacco at thecut end of cigarette or double cigarette are decreased.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a cigarette which canprevent shredded tobacco from dropping from the cut end thereof and issuitable for a higher-speed cigarette manufacturing machine.

To achieve the above object, a cigarette in accordance with the presentinvention comprises a shredded tobacco filler; a paper for wrapping thefiller, the paper having lap portion formed by both of side edgeportions to be lapped and bonded to each other; and means for increasinga coefficient of friction of the paper with respect to the filler.

According to the above-described cigarette, the inner surface of paperhas a high coefficient of friction with respect to the shredded tobaccofiller. Therefore, the paper firmly holds the shredded tobacco filler,so that the dropping of shredded tobacco from the cut end of cigaretteis decreased. In the process of manufacture of cigarettes, before theshredded tobacco filler is wrapped with the paper, the slip between thepaper and the filler is decreased. This decrease in slip inhibitsvariations in filling density in the tobacco rod, permits exact cuttingof tobacco rod, and reduces the breakage of shredded tobacco. Thisgreatly contributes to the prevention of dropping of shredded tobaccofrom the cut end of cigarette.

Specifically, the means for increasing the coefficient of frictionincludes frusto-pyramidal formulations or convex portions formed so asto be distributed on the inner surface of paper. These convex portionsbite into the shredded tobacco filler, so that the paper firmly holdsthe filler. The convex portions are formed at least at the paper portioncorresponding to the cut end portion of cigarette. Even in this case,the shredded tobacco is effectively prevented from dropping from the cutend of cigarette. The convex portions may be distributed in the wholearea of the paper, or in the whole area of the paper except both theside edge portions of the paper. In the case where the convex portionsare not formed at both the side edge portions of the paper, the sideedge portions are bonded well.

The convex portions are easily obtained by embossing the paper. It ispreferable that the embossing in this case increase the permeability ofpaper. If the permeability of paper is increased, the amount of carbonmonoxide in the tobacco smoke inhaled by a smoker is decreased, wherebythe ratio of carbon monoxide to tar is reduced.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 is a perspective view showing one embodiment of a filtercigarette;

FIG. 2 is an exploded perspective view of the filter cigarette shown inFIG. 1;

FIG. 3 is a perspective view showing a part of paper in an enlargedmanner;

FIG. 4 is a longitudinal sectional view of the tip end of the filtercigarette;

FIG. 5 is a schematic view showing a part of a cigarette manufacturingmachine equipped with an embossing apparatus;

FIG. 6 is a schematic view showing the embossing of paper; and

FIG. 7 is a front view of a measuring apparatus for coefficient offriction.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, a filter cigarette 1 comprises a cigarette 3and a filter 8. The cigarette 3 is formed by wrapping a shredded tobaccofiller, that is, a filler 2 with a paper 4. The filter 8 is connected toone end of the cigarette 3 by means of a tip paper 6. The tip endportion, that is, the S zone of the cigarette 3 has a higher fillingdensity of the filler 2 than other portions.

FIG. 3 shows a part of the paper 4 in an enlarged manner. The paper 4shown in FIG. 3 is expanded with the back surface up, and one side edgeportion 14 is also shown in the figure. That is, the paper 4 expands inthe direction of diagonal line toward the upper right in the figure.

As is apparent from FIG. 3, the back surface of the paper 4 has manyconvex portions 10, while the outside surface thereof has concaveportions 12 corresponding to the convex portions 10, except for both ofthe side edge portions 14 of the paper 4. The convex portions 10 arearranged in a matrix form, for example, having an arrangement of 40×40per 25.4 mm². In FIG. 3, the pitch and height of the convex portion 10are denoted by L (=0.64 mm) and H (=0.16 mm), respectively. Each convexportion 10 has a shape of a truncated pyramid. However, the convexportion 10 may have a shape of circular cone or triangular pyramid, orthe arrangement of convex portions may be formed with differently shapedconvex portions. Further, the pitch of the convex portions 10 may bechanged arbitrarily.

Both of the side edge portions 14 of the paper 4 are lapped and bondedto each other when the cigarette 3 is formed. Therefore, the side edgeportions 14 having no convex portions 10, are flat. However, the convexportions may be distributed over the whole back surface of the paper 4including the side edge portions 14, or may be distributed in the S zoneonly of the cigarette 3 (regardless of whether the convex portions 10are distributed at the side edge portions or not).

FIG. 4 is an enlarged sectional view of the tip end of the filtercigarette 1. As is apparent from FIG. 4, the convex portions 10 of thepaper 4 bite into the filler 2, so that a high frictional resistancearises between the paper 4 and the filler 2. This frictional resistancearises in all directions along the back surface of the paper 4.

According to the aforementioned cigarette 3, the filler 2 is wrappedfirmly and held by the paper 4 because of the presence of frictionalresistance between the paper 4 and the filler 2. As a result, the filler2, that is, the shredded tobacco does not move in the cigarette 3, sothat the shredded tobacco is prevented from dropping from the cut end ofthe cigarette 3.

FIG. 5 schematically shows a part of a cigarette manufacturing machinefor manufacturing the aforesaid cigarette 3. This cigarettemanufacturing machine is equipped with an embossing apparatus 16, andthis embossing apparatus 16 is disposed in the feed path of the paper 4.The embossing apparatus 16 has a frame 18, and a base 24 for this frame18 is installed on the floor via a plurality of legs 22. In the frame18, a pair of rollers 28 and 29 are arranged vertically to emboss thepaper 4. These rollers 28 and 29 can be rotated in the direction reverseto each other. The paper 4 is reeled out from a roll (not shown), andintroduced to between the rollers 28 and 29 via a plurality of guiderollers 26. The paper 4 having passed between the rollers 28 and 29 isfed to a rod forming section of the cigarette manufacturing machine viaa plurality of guide rollers 27.

The apparatus 16 is provided with a unit 30 for regulating a clearancebetween the rollers 28 and 29. Specifically, the regulating unit 30regulates the distance between the axes of the upper and lower rollers28 and 29. An air cylinder 32, which is installed on the base 24, pushesthe lower roller 29 toward the upper roller 28.

When the paper 4 passes between the rollers 28 and 29, a matrixarrangement of the convex portions 10 is formed in the whole area of thepaper 4 except both of the side edge portions 14, and thereafter thepaper 4 is fed to the rod forming section.

The following is a detailed description of the rollers 28 and 29.

As shown in FIG. 6, the lower roller 29 has an outer peripheral surface50 provided with protrusions of matrix arrangement corresponding to theconvex portions 10 of the paper 4, whereas the upper roller 28 has anouter peripheral surface 48 provided with holes corresponding to theprotrusions of the roller 29. Therefore, the rolls 28 and 29 rotatewhile these outer peripheral surfaces 48 and 50 engage with each other.

When the paper 4 passes between the upper and lower rollers 28 and 29,the outer peripheral surface 50, that is, the protrusion of the roller29 engages with the outer peripheral surface 48, that is, the hole ofthe roller 28 via the paper 4. Therefore, a matrix arrangement of theconvex portions 10 is formed on the back surface of the paper 4, andthis matrix arrangement of the convex portions 10 forms a matrixarrangement of the concave portions 12 on the outside surface of thepaper 4. In other words, the paper 4 except both of the side edgeportions is subjected to embossing. The convex portions 10 formed byembossing, thus, increase the permeability of the paper 4.

Subsequently, the paper 4 is fed to the rod forming section of thecigarette manufacturing machine as shown in FIG. 5. At the rod formingsection, the stream of shredded tobacco is wrapped with the paper 4, bywhich a tobacco rod R is formed continuously.

The cigarette manufacturing machine will be described briefly.

The cigarette manufacturing machine is provided with a conveyor unit 40,which has a suction belt, that is, a conveyor belt 42. The conveyor belt42 sucks shredded tobacco in a layer form from a chimney 38, so that ashredded tobacco layer T_(L) is formed on the lower surface of theconveyor belt 42. This shredded tobacco layer T_(L) is conveyed to therod forming section as the conveyor belt 42 runs. In this conveyingprocess, the thickness of the shredded tobacco layer T_(L) is controlledby a trimming apparatus 44, so that portions having an increasedthickness are formed periodically in the shredded tobacco layer T_(L).

Subsequently, the shredded tobacco layer T_(L) is supplied from theconveyor belt 42 onto the paper 4. The paper 4 is lapped over agarniture belt 46, so that the paper 4 passes through the rod formingsection together with the shredded tobacco layer T_(L) as the garniturebelt 46 runs. The garniture belt 46, which is set around via a pluralityof rollers, runs in the direction of the arrow in FIG. 5 as the drivingdrum (not shown) is rotated.

At the rod forming section, the shredded tobacco layer T_(L) is wrappedwith the paper 4 as publicly known, by which the tobacco rod R is formedcontinuously. At the rod forming section, glue is applied to one sideedge of the paper 4, and both of the side edges of the paper 4 arebonded to each other by being lapped.

In the above-described cigarette manufacturing machine, the paper 4 andthe shredded tobacco layer T_(L) are carried at a high speed togetherwith the garniture belt 46. At this time, the shredded tobacco layerT_(L) and the paper 4 are carried together by the frictional resistancebetween them. Since the paper 4 has been embossed, the frictionalresistance between the paper 4 and the shredded tobacco layer T_(L) ishigh, so that a slip of the shredded tobacco layer T_(L) with respect tothe paper 4 is decreased.

Subsequently, at the cutting section of the cigarette manufacturingmachine, the tobacco rod R is cut exactly at the aforesaid portionswhere the thickness of the shredded tobacco layer T_(L) is increased, bywhich a cigarette or double cigarette is formed. The double cigarette issupplied to a filter attachment, where filter cigarettes 1 are formed.

If the cigarette manufacturing machine is provided with theaforementioned embossing apparatus 16, a special paper need not be used,and the tobacco rod R can be formed while the ordinary paper isembossed. Therefore, even if the operation speed of the cigarettemanufacturing machine is increased, the slip of the shredded tobaccolayer T_(L) with respect to the paper 4 is decreased, so that thetobacco rod R is cut exactly.

The aforementioned embossing apparatus 16 embosses the paper 4 exceptboth of the side edge portions 14 thereof. The rollers 28 and 29 of theembossing apparatus 16 may emboss the whole surface of the paper 4, orembosses the paper 4 periodically. In the latter case, protrusion orhole distributing regions are provided at intervals in thecircumferential direction of roller on the outer surfaces of the rollers28 and 29.

If the paper 4 has been embossed in advance, the cigarette manufacturingmachine need not be equipped with the embossing apparatus 16.

FIG. 7 shows an apparatus for measuring the coefficient of friction ofthe paper 4. This measuring apparatus mainly includes a base 54, a guiderod 56, a sample table 58, a support 60, and a load sensor 62. The guiderod 56 extends horizontally just above the base 54, and both ends of theguide rod 56 are supported by the base 54 via legs 64. The sample table58 extends horizontally just above the guide rod 56, and has a slider 66at each end thereof. The slider 66 is attached to the guide rod 56.Therefore, the sample table 58 is supported in such a manner as to bemovable along the guide rod 56. A part of the paper 4 having beenembossed can be set on the sample table 58 as a sample P.

The support 60 has a shape such as to stride over the sample table 58.The lower end of the support 60 is attached to the guide rod 56 via aslider 70. The support 60 is provided with a load applying rod 68, whichis movable vertically. The load applying rod 68 has a receiving face fora weight 72 at the upper end thereof. A space capable of containingshredded tobacco T is formed in the support 60, and the shredded tobaccoT in this space is held between the lower end of the load applying rod68 and the sample P on the sample table 58. Therefore, the shreddedtobacco T in the space is subjected to a load corresponding to the loadapplying rod 68 and the weight 72.

One leg 64 of the guide rod 56 is fitted with the load sensor 62. Theload sensor 62 and the support 60 are connected to each other via a pairof hooks 74 and a wire 76. The load sensor 62 is fixed to the leg 64 ofthe guide rod 56, and the movement of the support 60 in the directionalong the guide rod 56 is restricted.

When being subjected to a tensile force via the wire 76, the load sensor62 can display the value of the tensile force in units of weight at thedisplay portion (not shown).

The following is a description of a procedure for measuring thecoefficient of friction of the sample P.

First, the sample P is set on the sample table 58. The sample P has alength of 100 mm. Then, 1 g of shredded tobacco T is set in the space inthe support 60, that is, on the sample P. Thereby, the measurement ofthe coefficient of friction of the sample P is made possible.

If the sample table 58 is pulled in the direction indicated by the arrowin FIG. 7 via a handle 59, the support 60 is subjected to a drag forcecaused by the frictional resistance between the sample P and theshredded tobacco T. This drag force is transmitted to the load sensor 62via the wire 76. The load sensor 62 detects and displays the drag force,that is, the frictional resistance between the sample P and the shreddedtobacco T.

If the pulling force of the sample table 58 increases further, thefrictional resistance also increases. Thereafter, the sample tableovercomes the frictional resistance and begins to move in the directionindicated by the arrow in FIG. 7. At this time, the detection value ofthe load sensor 62 is read, and this detection value indicates a staticfrictional resistance between the sample P and the shredded tobacco T,that is, a static frictional force. When the sample table 58 is movedstably, the detection value of the load sensor 62 indicates a kineticfrictional force. By dividing the static frictional force and kineticfrictional force thus obtained by the load given to the shredded tobaccoT, a coefficient of static friction and coefficient of dynamic frictionare calculated, respectively.

The above-mentioned measurements were made five times each on four kindsof samples P. The measurement results are given in Table 1. Themeasurement results given in Table 1 are average values. The samples P1to P3 each are a part of embossed paper, but has a different shape ofthe convex portion 10. The sample P4 is a part of flat paper.

                  TABLE 1                                                         ______________________________________                                        Static friction     Kinetic friction                                          Frictional   Coefficient                                                                              Frictional                                                                              Coefficient                                 force (gf)   of friction                                                                              force (gf)                                                                              of friction                                 ______________________________________                                        Sample P1                                                                            535.8     1.072      486.9   0.974                                     Sample P2                                                                            528.1     1.056      429.1   0.858                                     Sample P3                                                                            563.9     1.128      500.4   1.001                                     Sample P4                                                                            443.0     0.886      403.0   0.806                                     ______________________________________                                    

As is apparent from the measurement results in Table 1, the samples P1to P3 have a high frictional force and coefficient of friction than thesample P4.

Next, comparison was made between the manufacture of filter cigaretteusing an ordinary paper P4 and the manufacture of filter cigarette usingembossed papers P5 and P6 regarding the quantity of shredded tobaccodropping from the cigarette. In this case, the concave portions of thepapers P5 and P6 had depths of 55 μm and 65 μm, respectively.

The dropping quantity of shredded tobacco is a difference between thereference filling quantity of shredded tobacco corresponding onecigarette of tobacco rod R and the actual filling quantity of shreddedtobacco in a filter cigarette. By dividing the dropping quantity ofshredded tobacco by the reference filling quantity, a dropping ratio canbe obtained.

If the difference between the standard dropping quantity of shreddedtobacco in the cigarette manufactured using the paper P4 and thedropping quantity of shredded tobacco in the cigarette manufacturedusing the embossed papers P5 and P6 is divided by the standard droppingquantity, the divided value indicates a dropping quantity reductionratio in the case where an embossed paper is used.

The dropping ratio and dropping quantity reduction ratio of shreddedtobacco for the papers P4 to P6 are given in Table 2.

                  TABLE 2                                                         ______________________________________                                                           Dropping quantity reduction                                        Dropping ratio (%)                                                                       ratio (%)                                                  ______________________________________                                        Paper P4  1.91         --                                                     Paper P5  1.32         30.9                                                   Paper P6  1.47         23.0                                                   ______________________________________                                    

As is apparent form Table 2, the filter cigarettes using the papers P5and P6 have a lower dropping ratio than the filter cigarette using thepaper P4, and the embossing of paper greatly improves the dropping ratioof shredded tobacco.

Next, a smoking test was made on the filter cigarette using the paper P4and the filter cigarette using an embossed paper P7. In this smokingtest, the ratio of the weight of carbon monoxide to the weight of tar intobacco smoke inhaled by a smoker, that is, the CO/T ratio per onefilter cigarette was measured. The measurement results are given inTable 3. For the paper P7, the concave portion 12 has a depth of 85 μm.

                  TABLE 3                                                         ______________________________________                                                     CO/T                                                             ______________________________________                                                Paper P4                                                                             1.04                                                                   Paper P7                                                                             0.94                                                           ______________________________________                                    

As is apparent from Table 3, the filter cigarette using the embossedpaper P7 has a lower CO/T ratio than the filter cigarette using thepaper P4. This is probably because the permeability of the paper 4 isincreased by embossing, whereby the oxidation of CO is accelerated.

According to the cigarette or filter cigarette in accordance with thepresent invention, both of the coefficient of static friction and thecoefficient of dynamic friction between the paper and the shreddedtobacco filler increase. Therefore, the embossed paper firmly holds theshredded tobacco filler, so that the shredded tobacco is prevented fromdropping from the cut end of cigarette or filter cigarette. The droppingof shredded tobacco is also reduced in the process of manufacture ofcigarettes or filter cigarettes.

Even if the operation speed of a cigarette manufacturing machine isincreased, the slip between the paper and the shredded tobacco layer isdecreased. This decrease in slip permits exact cutting of tobacco rod atthe portions where the thickness of shredded tobacco layer is increased,and reduces the breakage of shredded tobacco. This greatly contributesto the prevention of dropping of shredded tobacco from the cut end ofcigarette or double cigarette.

Further, according to the cigarette or filter cigarette in accordancewith the present invention, the CO/T ratio of tobacco smoke inhaled by asmoker is decreased.

The invention being thus described it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art intended tobe included within the scope of the following claims.

We claim:
 1. A cigarette comprising:a shredded tobacco filler; a paperfor wrapping said filler, said paper having a lap portion formed by bothof the paper side edge portions to be lapped and bonded to each other;and a matrix of frusto-pyramidal formations on an interior surface areaof said paper, the frusto-pyramidal formations increasing a coefficientof friction of said paper with respect to said filler.
 2. The cigaretteaccording to claim 1, wherein said frusto-pyramidal formations areformed at least at a paper portion corresponding to the cut end ofcigarette.
 3. The cigarette according to claim 1, wherein saidfrusto-pyramidal formations are formed on a surface area of said paperexcept on at least one side edge portion of said paper.
 4. The cigaretteaccording to claim 1, wherein said frusto-pyramidal formations areformed on an entire surface area of said paper.
 5. The cigaretteaccording to claim 1, wherein said frusto-pyramidal formations areobtained by embossing said paper.
 6. The cigarette according to claim 5,wherein said frusto-pyramidal formations increase the permeability ofsaid paper.
 7. The cigarette as defined in claim 1, further comprising afilter.
 8. The cigarette as defined in claim 1, wherein thefrusto-pyramidal formations are formed as adjacent rows offrusto-pyramids.
 9. The cigarette as defined in claim 8, wherein basesof at least two frusto-pyramidal formations are separated by a flatsurface of said paper.
 10. The cigarette as defined in claim 9, whereinsaid flat surface is formed along at least one tetragonal side of eachfrusto-pyramidal formation.
 11. The cigarette as defined in claim 1,wherein an apex and at least one side of each of said frusto-pyramidalformations are formed along a line extending at an interior obtusedownward angle.
 12. The cigarette as defined in claim 11, wherein eachof said frusto-pyramidal formations has four sides extending downward toform a base.
 13. The cigarette as defined in claim 12, wherein said apexof each of said frusto-pyramidal formations is flat, the flat surface ofsaid apex is a plane in parallel with the surface of the paper.
 14. Thecigarette as defined in claim 13, wherein said apex has a surface arealess than the surface area formed by said base of each of saidfrusto-pyramidal formations, said apex and said base formed in twoparallel planes.
 15. The cigarette as defined in claim 1, wherein thematrix of frusto-pyramidal formations is arranged at least 40×40 per25.4 mm² of paper.
 16. The cigarette as defined in claim 1, wherein atleast one frusto-pyramidal formation is separated from an adjacentfrusto-pyramidal formation by a distance of at least 0.64 mm, thedistance measured from a near proximity flat surface of an apex of saidat least one frusto-pyramidal formation to a far proximity flat surfaceside apex of said adjacent frusto-pyramidal formation.